Calculate texture clamping X/Y coordinates in parallel.
Calculate texture clamping X/Y coordinates in parallel.

The X and Y values of `clampedCoord`, `extraRepeatCoord`, and `snapped`
were being calculated and stored separately, even in cases where work
could easily be done in tandem. Updated the code so that we use .xy when
it makes sense to do so.

Change-Id: I10d85670acb4fec960444b3f3c30f2929c6dcaf2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/318436
Auto-Submit: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>
Reviewed-by: Brian Salomon <61fabaaf0876044aeedfd8e351e485c028d69e7b@google.com>
Commit-Queue: Brian Salomon <61fabaaf0876044aeedfd8e351e485c028d69e7b@google.com>
Commit-Queue: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>

google/skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia